52 THE NAUTILUS. 



Length 7.75; width 4; aperture length 3.25; width 2 mm. 



Length 8; width 3.50; aperture length 3.50; width 2 mm. 



Length 7; width 3.50; aperture length 3.25; width 2 mm. 



Habitat: Twelve miles west of Cleveland, Ohio, in a small, swampy 

 brook. 



This curious species was at first thought to be Lea's exigua but his 

 description does not cover the present species and the figure is totally 

 unlike it. The type of exigua is not in existence. It is probably a 

 small form of desidiosa and its best disposition would seem to be as 

 a synonym under that species. 



L. sterkii is narrower than Jiumilis, the whorls are more shouldered 

 and the aperture is much more oval. The wide-spreading columella 

 callus is also different and peculiar. It has a superficial resemblance 

 to owascoensis Baker, but that species has six full whorls, the whorls 

 are more shouldered, the aperture is more elliptical, the umbilicus is 

 more open and the columella callus is not so wide. Juvenile speci- 

 mens are rounder and more robust than the adult forms. 



The specimens were collected by Dr. Victor Sterki, to whom the 

 species is dedicated. 



Lymnea parva Lea, Proc. Am. Phil. Soc., II, 33, 1841. 



Shell very small, thin, ovate-conic, turreted ; color greenish-horn ; 

 surface dull, marked by heavy, crowded growth lines ; protoconch 

 very small, rounded, light-horn colored ; whorls 4-J, rounded and 

 shouldered ; spire obtusely conic, turreted, a trifle longer than the 

 aperture ; sutures very deeply impressed ; aperture roundly ovate ; 

 peristome thin, acute ; columella almost straight, covered with a 

 rather heavy callus which is reflected over the flat parietal wall and 

 also forms an erect border to the umbilicus, which is open and deep. 



Length 3.25; width 2; aperture length 1.50; width 1 mm. 



Length 4 ; width 2 ; aperture length 2 ; width 1 mm. 



Length 3; width 2 ; aperture length 1.25 ; width .9 mm. 



Length 4.25 ; width 2 ; aperture length 1.75 ; width 1 mm. 



Habitat: marsh on Lake James, Steuben Co., Indiana (Daniels); 

 Cincinnati, Ohio (Lea); Lilycash Creek, Joliet, 111. (Handwerk); 

 Northern Illinois, in drift (Sterki). 



This little species, the smallest of our American Lymna^as, belongs 

 to the section of this genus typified by humilis Say and curta Lea. 

 It is more nearly related to curta, appearing at first sight to be a 



